Metal oxides are compounds composed of metal atoms bonded to oxygen atoms and are used as coating materials in the industry. As shown in Table 1 below, metal oxides have characteristic densities.
Metal oxides include yttrium oxide (Y2O3), aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), tin oxide (SnO), iron oxide (FeO), titanium oxide (TiO2), zirconium oxide (ZrO2), chromium oxide (Cr2O3), hafnium oxide (HfO), beryllium oxide (BeO) and the like. As shown in Table 1 below, such metal oxides are stoichiometric compounds in which the atomic number of each of elements forming the metal oxides is a simple integer.
In a process of forming a metal oxide layer by coating metal oxide on the surface of any substrate in various industrial fields, the density of the metal oxide layer compared to the metal oxide before coating is important. In other words, as the density of the metal oxide layer is closer to the density of the metal oxide before coating, the metal oxide layer exhibits better physical or chemical properties. In addition, the more density of the metal oxide layer increases, the more surface hardness thereof also increases. Table 1 below summarizes the atomic number of each element in each metal oxide, the atomic percent of each element in each metal oxide, and the density of each metal oxide.
TABLE 1MetalEle-AtomicAtomicEle-AtomicAtomicDensityoxidementnumberpercentmentnumberpercent(g/cm3)Al2O3Al240.00O360.004.100Ti2O3Ti133.33O266.674.230SnOSn150.00O150.006.450SnO2Sn133.33O266.676.950ZrO2Zr133.33O266.675.680Y2O3Y240.00O360.005.010CrO3Cr125.00O375.002.700Cr2O3Cr240.00O360.005.220HfO2Hf133.33O266.679.680BeOBe150.00O150.003.010MgOMg150.00O150.003.580FeOFe150.00O150.005.745Fe2O3Fe240.00O360.005.242ZnOZn150.00O150.005.606BaOBa150.00O150.005.720
Meanwhile, in the fabrication of semiconductor devices, light-emitting diodes (LEDs), solar cells, display devices and the like, processes including deposition, etching, ashing, diffusion, cleaning and the like are performed. During such processes, impurities (particles) generated during the processes adhere to the surfaces of substrates in process chambers, and then are detached during the processes to thereby contaminate wafers. Thus, substrate surfaces are required to have anti-particle adhesion so as to minimize the adhesion of such particles to the substrate surfaces.
In addition, if a substrate having poor anti-particle adhesion is used in a process, the process should be stopped in order to clean the substrate contaminated with particles, and the substrate should be taken out of the process chamber and cleaned ex-situ, before the process is re-initiated. On the other hand, a substrate having anti-particle adhesion imparted to the surface is used in a process, in-situ cleaning can be performed by a wet or dry process in a state in which the process is not stopped and in which the process chamber is not opened, and thus the cycle of ex-situ cleaning can be extended, resulting in a significant increase in productivity and yield. Thus, substrates are required to have anti-particle adhesion in such processes.
Furthermore, substrates are required to have, in addition to anti-particle adhesion, anti-plasma and anti-corrosion properties. This is because the substrates are exposed not only to fluorine-based gas plasma such as nitrogen fluoride (NF3) in a deposition process, but also to corrosive gases such as chlorine-based gases (e.g., boron chloride (BCl), etc.) or fluorine-based gases (e.g., carbon fluoride (CF4), etc.), which are used as etching gases in an etching process.
Meanwhile, in conventional technologies for making structures formed of crystalline particles and amorphous particles, References 1 and 2 below disclose a mechanism in which an amorphous coating layer is formed on a substrate using pulsed laser deposition (PLD; a kind of physical vapor deposition (PVD)) by irradiating a laser onto a target composed of a coating material (YSZ; yttria-stabilized zirconia) to vapor-deposit the coating material onto the substrate in a vacuum state, and the amorphous coating layer is crystallized by heating it to a temperature ranging from several tens to hundreds of degrees centigrade (° C.).